Matrix effect on the photoluminescence of Si nanocrystal

To examine the matrix effect on the light emission of Si nanocrystal (Si-NC), we investigated the photoluminescence (PL) of Si-NC from multilayered samples of Si/SiO2 and SiO/SiO2 and single-layered pure Si thin films, which had all been annealed in nitrogen at 1,100 °C for 1 h so as to form Si-NCs. The size range of Si-NC is 1–10 nm. It was found that the density of Si-NC in the pure Si> that in Si/SiO2> that in SiO/SiO2, but the PL intensity of Si-NC from pure Si< that from Si/SiO2< that from SiO/SiO2. On the other hand, the PL intensity of Si-NC from Si/SiO2 sample is higher than that from Si/Si3N4 one. All these results are related to the difference in matrix surrounding Si-NCs, which causes differences in carrier confinement or/and interface state. The results suggest that for light emission of Si-NC, the matrix effect is determinative, and can be more important than the density of Si-NC itself.